PIL: Image resizing : Algorithm similar to firefox's

Question

I\'m getting about the same bad looking resizing from all the 4 algorithms of PIL

>>> data = utils.fetch(\"http://wavestock.com/images/beta-ico         


        

Answer 1

The image posted is an indexed image. Its mode is 'P' if you read it via PIL. The PIL documentation on Image.resize() for the resample parameter states that:

If the image has mode “1” or “P”, it is always set to PIL.Image.NEAREST

So PIL will use nearest filter for resizing indexed images, which is a low quality filter.

The right way is to convert the image mode to RGB and then use resize with a high-quality filter such as Image.LANCZOS. By the way, Image.ANTIALIAS is now the same as Image.LANCZOS, source here.

import Image
img = Image.open("beta-icon.gif").convert("RGB")
img = img.resize((36,36), Image.LANCZOS)
img.save("img-resized.png")